UNIVERSITY  OF  CALIFORNIA  PURLICATIONS. 


COLLEGE  OF  AGRICULTURE, 


AGRICULTURAL  EXPERIMENT  STATION. 


THE  VALUE  OF  OAK  LEAVES  FOR  FORAGE. 


By  W.  W.  MACKIE. 


Signal  Peak,  in  eastern  Mendocino  County. 

Slopes  covered  with  low-growing  Quercus  garryana,  and  open  places  where  covering  has  been 
killed  by  sheep.  In  the  foreground  is  False  Hellebore  ( Veratrum),  an  indication  of 
moist  ground. 


BULLETIN  No.  150 

(Berkeley,  April,  1903,)       .    . 


W.    W.    SHANNON, 


SACRAMENTO: 

:     :     :     superintendent  state  printing. 
1903. 


BENJAMIN  IDE  WHEELER,  Ph.D.,  LL.D.,  President  oj  the  University. 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist. 

E.  J.  WICKSON,  M.A.,  Horticulturist,  and  Superintendent  of  Central  Station  Grounds. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S.,  C.E.,  Irrigation  Engineer. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.    {Soils  and  Alkali.) 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

M.  E.  JAFFA,  M.S.,  Assistant  Chemist.    (Foods,  Fertilizers.) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.    (Soils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.    (Fruits,  Waters,  Insecticides.) 

RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian,  Bacteriologist. 

E.  H.  TWIGHT,  B.Sc,  Diploma  E. A.M.,  Viticulturist. 

E.  W.  MAJOR,  B.Agr.,  Dairy  Husbandry. 

A.  V.  STQBENRAUCH,  M.S.,  Assistant  Horticulturist  and  Superintendent  of  Substations. 

WARREN  T.  CLARKE,  Assistant  Field  Entomologist. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

C.  A.  TRIEBEL,  Ph.G.,  Student  Assistant  in  Agricultural  Laboratory. 

C.  A.  COLMORE,  B.S.,  Clerk  to  the  Director. 


EMIL  KELLNER,  Foreman  of  Central  Station  Grounds. 
JOHN  TUOHY,  Patron, 


,    Tulare  Substation,  Tulare. 
JULIUS  FORRER,  Foreman, 

R.  C.  RUST,  Patron,  ) 

Y  Foothill  Substation,  Jackson. 
JOHN  H.  BARBER,  Foreman,  ) 

S.  D.  MERK,  Patron,  ) 

y  Coast  Range  Substation,  Paso  Robles. 
J.  H.  OOLEY,  Workman  in  charge,  ) 

S.  N.  ANDROUS,  Patron,  )  ,  (  Pomona. 

>•  Southern   California  Substation,  •< 
J.  W.  MILLS,  Foreman,     )  (  Ontario. 

V.  C.  RICHARDS,  Patron,         ) 

V  Forestry  Station,  Chico. 
T.  L.  BOHLENDER,  in  charge,  ) 

ROY  JONES,  Patron 

WM.  SHUTT,  Foreman 


t  Forestry  Station,  Santa  Monica. 


The  Station  publications  (Reports  and  Bulletins)  will  be  sent  to  any 
citizen  of  the  State  on  application,  so  long  as  available. 


THE  VALUE  OF  OAK  LEAVES  FOR  FORAGE. 


The  exploration  in  the  course  of  which  the  data  and  samples  forming  the  basis  of 
this  bulletin  were  gathered,  was  originated  by  the  Bureau  of  Forestry  of  the  Depart- 
ment of  Agriculture,  with  a  view  to  a  study  of  the  forest  resources  of  the  region  in 
question.  At  my  request,  Mr.  Mackie  paid  some  attention  to  the  pasture  conditions 
existing  there,  to  serve  as  a  complement  to  the  previous  exploration  of  Mr.  Joseph 
Burtt  Davy  in  northwestern  California,  the  results  of  which  were  published  in  Bulletin 
No.  12,  of  the  Bureau  of  Plant  Industry  of  the  Department.  Mr.  Mackie  found  some- 
what unexpectedly  that  a  large  part  of  the  actual  nourishment  of  stock  in  the  region 
was  obtained  by  browsing  on  the  various  oaks,  and  on  his  return  I  suggested  to  him, 
as  an  interesting  subject  for  his  graduating  thesis,  an  examination  of  the  chemical 
composition  and  nutritive  value  of  the  several  kinds  of  oak  leaves  usually  eaten  by 
stock.  The  results  of  this  work,  carried  out  in  the  Station  laboratory,  together  with 
the  general  information  obtained  regarding  the  importance  of  browsing  forage  as 
against  the  rapidly  deteriorating  grass  range,  form  the  subject  of  this  paper. 

E.  W.  HILGARD. 


During  the  summer  and  fall  of  1902,  while  experting  a  forest  reserve 
in  the  northern  Coast  Ranges,  the  writer  noticed  with  surprise  and 
interest  the  eagerness  with  which  leaves  of  certain  oaks  were  eaten  by- 
live  stock.  Having  this  fact  in  mind,  many  observations  were  made  in 
regard  to  the  forage  value  of  each  species  of  oak  occurring  in  the  Coast 
Ranges.  These  observations,  while  confined  more  especially  to  the 
extent  to  which  each  species  was  eaten  by  stock,  included  also  the 
range  or  distribution,  altitude,  and  mode  of  occurrence. 

Later  in  the  year,  in  order  to  ascertain,  if  possible,  whether  these 
observations  indicated  fully  the  real  value  and  significance  of  these 
oaks  for  forage,  a  chemical  analysis  was  undertaken  covering  six  species 
of  oaks  and  one  of  poison  oak.  Only  those  species  were  chosen  which 
occur  on  hills,  ridges,  and  mountains  where  tillage  is  impossible;  and 
the  object  kept  continually  in  mind  was  the  forage  value  of  the  leaves 
of  the  different  species. 

It  is  the  purpose  of  this  paper  to  give  in  full  the  results  of  both 
observation  and  analysis,  and  to  discuss  the  harmony  or  lack  of 
harmony  between  the  two. 

The  ranges  covered  by  the  investigation  are  those  situated  in  Lake 
County,  in  eastern  Mendocino  north  of  Ukiah  to  Humboldt  County,  in 
the  western  parts  of  Colusa  and  Glenn  counties,  and  in  southwestern 


4  UNIVERSITY    OF   CALIFORNIA — EXPERIMENT   STATION. 

Tehama  County.  These  northern  Coast  Ranges  are  broken  up  into  many 
ridges,  all  running  northwest  and  southeast.  Between  them  are  small, 
narrow,  gravelly  valleys,  with  very  little  cultivable  soil.  The  moun- 
tains and  slopes  are  composed  of  shales  or  loose  soft  rocks,  often  volcanic 
in  formation.  The  soil  formed  by  decomposition  of  these  rocks  on  ridges 
is  very  shallow  and  poor — seldom  as  deep  as  four  feet  and  commonly 
two  or  less.  The  decomposition  of  these  shales  is  hastened  by  the  growth 
of  chaparral,  herbs,  and  grasses,  and  on  these  poor,  shallow,  rocky  soils 
the  browsing  oaks  are  found.  In  the  sedimentary  or  alluvial,  or  even 
the  colluvial  soils  washed  from  these  mountains,  none  of  the  browsing 
oaks  are  found.  These  oaks,  therefore,  are  good  indicators  of  poor,  shal- 
low, and  rocky  soils. 

This  area  is  typical  of  all  the  northern  Coast  Ranges,  and,  in  regard 
to  oaks,  may  be  taken  also  as  a  type  of  the  southern  Coast  Ranges. 
Thus  the  browsing  areas  of  the  Coast  Ranges  alone  cover  about  one  third 
of  the  State.  Adding  to  these  those  areas  of  the  lower  foothills  of  the 
Sierra  Nevada,  which  are  occupied  in  part  by  many  of  these  same 
species  of  oaks,  we  have,  as  the  entire  region  enriched  in  many  places 
by  browsing  oaks,  about  one  half  the  State  area. 

Of  the  six  species  of  oaks  chosen  from  this  browsing  area  for  investi- 
gation and  here  discussed,  three  are  peculiar  to  California.  The  remain- 
ing three  species  (Quercus  garryana,  Q.  californica,  and  Q.  chrysolepis) 
range  north  into  Oregon,  as  also  does  the  Poison  Oak,  a  species  of 
sumach.  Each  of  these  oaks  varies  in  range  according  to  temperature, 
altitude,  and  humidity;  and  the  value  of  each  species  as  a  "browse" 
increases  almost  directly  with  the  altitude,  except  when  modified  by 
exposure  to  the  direct  rays  of  the  sun.  Beginning  on  the  lower  hills, 
the  six  species  succeed  one  another  upward  in  nearly  distinct  zones  or 
ranges,  as  follows:  Blue  Oak  (Quercus  douglasii),  Scrub  Oak  and  Curl- 
leaf  Scrub  Oak  (Q.  dumosa  and  its  variety,  bullata),  Canon  Live  Oak 
(Q.  wisiizeni),  Maul  Oak  (Q.  chrysolepis),  Black  Oak  (Q.  californica), 
and  White  Mountain  Oak  (Q.  garryana).  In  addition  to  these,  the 
Poison  Oak  (Rhus  diversiloba)  is  found  commonly  everywhere,  on  hills, 
slopes,  and  by  streams. 

In  the  following  description  we  will  attempt  to  characterize  each  indi- 
vidual species  in  the  above  order,  as  regards  form,  mode  of  occurrence, 
range,  and  the  forage  value  as  indicated  by  the  stock  feeding  upon  it. 

BLUE   OAK  (Quercus  douglasii). 

The  Blue  or  Rock  Oak  reaches,  in  favored  localities,  a  height  of  20 
feet,  but  is  commonly  found  as  a  small  tree  about  12  feet  high,  or  as  a 
shrub  from  4  to  6  feet  in  height.  It  is  oval  or  round  in  appearance, 
and  is  covered  densely  with  dark  bluish  leaves.  The  leaves  are  obovate 
to  oblong,  with  lobes  commonly  increasing  in  size  toward  the  apex.     In 


VALUE  OF  OAK  LEAVES  FOR  FORAGE.  5 

young  trees  and  shrubs  the  leaves  are  inclined  to  become  spinescent. 
The  acorns,  borne  in  shallow  cups,  are  oval  to  ovate- acute,  and  are 
about  1  to  1^  inches  long. 

In  altitude,  this  oak  is  limited  to  the  low  foothills  and  dry  valleys 
where  the  soil  is  hard  and  rocky,  and  never  ranges  upward  to  the  higher 
slopes  and  valleys.     It  is  found  most  abundantly  in  the  dry  foothills  of 


PLATE   I.      QUERCUS  DOUGLAS1I.      (BLUE    OAK.) 


the  inner  Coast  Ranges,  but  extends  from  Mendocino  County  and  the 
upper  Sacramento  Valley  through  the  Coast  Ranges  and  Sierra  Nevada 
to  Tejon  Pass,  in  Kern  County,  from  whence  stunted  individuals  extend 
to  the  margin  of  the  Mojave  Desert.  In  the  southern  Coast  Ranges  it 
reaches  its  maximum  height  of  fully  30  feet. 


6 


UNIVERSITY   OF   CALIFORNIA — EXPERIMENT    STATION. 


On  account  of  the  dryness  of  its  leaf,  only  goats  and  sheep  browse  on 
the  Blue  Oak;  but  the  acorn  mast,  which  is  plentiful  and  quite  certain, 
is  excellent  feed  for  hogs,  cattle,  sheep,  goats,  and  often  for  horses. 


m 

■ 

■■■ 

•  &  ■ 

.; 

SCRUB    OAK  (Quercus  dumosa). 

This  oak  is  a  round-topped  shrub  5  or  6  feet  high,  consisting  of 
numerous  closely  tangled  branches  starting  from  near  the  ground.  The 
twigs  are  usually  tomentose,  with  leaves  bunched   at  the  ends.     The 


VALUE  OF  OAK  LEAVKS  FOR  FORAGE. 


leaves  are  oblong  to  obovate  and  entire  on  the  older  trees,  but  are  often 
sinuate-toothed  and  spinescent  in  young  shrubs.  They  are  pale  green 
in   color  and   pubescent  on   the  lower  side.     The  acorns  are  oval  and 


PLATE   III.      QlTERCUS   DUMOSA.      (SCRUB    OAK.) 


pointed,  from  \  to  1-J  inches  long,  and  are  contained  in  shallow  cups. 
The  crop  is  light  and  very  uncertain. 

The  Scrub  Oak  is  commonly  found  associated  with  many  other  shrubs 
in  the  chaparral  of  the  mountains  and  upper  foothill  slopes  in  dry 


8 


UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION. 


localities.  It  ranges  from  Mendocino  County  southward  through  the 
Coast  Ranges  to  Lower  California,  and  is  also  found  in  the  foothills  of 
the  Sierra  Nevada. 

This  shrub,  on  account  of  its  low  habit  of  growth,  is  particularly 
adapted  to  browsing,  and  is  one  of  the  best  for  sheep  and  goats.  Cattle, 
however,  dislike  it  on  account  of  its  harsh,  spinescent  leaves,  but  feed  on 
it  during  the  winter  when  snow  has  covered  the  ground,  or  when  from 
any  cause  other  food  is  not  available. 


PLATE   IV.     QUERCUS  DUMOSA,  VAR.  BULLATA.    (CURL-LEAF  SCRUB   OAK.) 


CURL-LEAF  SCRUB  OAK  (Quercus  dumosa,  var.  bullata). 

The  Curl-leaf  Scrub  Oak  is  a  variety  with  the  same  habit  of  growth 
as  the  typical  species.  The  leaves  differ,  however,  in  having  the  mar- 
gins strongly  re  volute,  thus  presenting  a  curled  appearance.  The  under 
side  of  the  leaf  is  densely  tomentose,  and  the  whole  leaf  is  thicker  and 
rounder  than  that  of  the  type.  The  acorns  of  the  variety  are  similar  in 
size  and  shape  to  those  of  the  other,  but  are  contained  in  even  shallower 
cups. 


VALUE  OF  OAK  LEAVES  FOR  FORAGE. 


9 


This  oak  is  seldom  found  south  of  San  Francisco  Bay,  and  reaches  its 
greatest  abundance  north  of  Clear  Lake,  on  the  dry  eastern  slopes  of  the 
Coast  Ranges  bordering  on  the  Sacramento  Valley,  and  extending  to 
Mount  Shasta. 

The  forage  value  of  the  variety  is  apparently  the  same  as  that  of  the 
type  of  the  species. 


PLATE  V.    Quercus  wislizeni.    (Canon  Live  Oak.) 


CANON   LIVE   OAK  {Quercus  wislizeni). 

The  Canon  Live  Oak  when  found  in  the  canons  is  a  tree  usually  20 
to  40  feet  high,  but  when  it  passes  into  the  chaparral  it  is  never  higher 
than  8  feet.  Here  it  is  an  intricately  branched  shrub  with  a  rounded 
top.  The  bark  on  old  trees  is  rough  and  thick,  but  on  shrubs  it  is 
smooth.  The  leaves  are  usually  oblong-lanceolate,  entire,  serrate  or 
dentate,  and  are  lustrous  and  dark  green  in  color.  They  are  about  li 
inches  long  and  |  of  an  inch  wide.    The  nuts  ripen  in  the  second  season, 


10 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 


and  are  long,  sessile,  slender  oblong-oval,  set  in  deep  scaly  cups.     The 
mast  is  usually  scanty. 

The  shrub  is  common  in  the  chaparral  with  Quercus  dumosa,  and 
ranges  with  it  in  altitude.  It  is  well  distributed  in  the  Coast  Ranges 
from  Mount  Shasta  to  San  Diego  County,  usually  at  quite  a  distance 


PLATE  VI.    Quercus  chrysolepis.    (Maul  Oak.) 
Showing  two  distinct  leaf  forms. 

from  the  sea.     It  also  exists,  but  not  commonly,  from  Mount  Shasta 
through  the  lower  foothills  of  the  Sierra  to  Tejon  Pass. 

The  leaves  of  this  shrub  are  sought  in  preference  to  those  of  the 
Scrub  Oak  by  sheep,  goats,  and  cattle,  and  it  is  thus  often  found 
stripped  of  its  leaves. 


VALUE  OF  OAK  LEAVES  FOR  FORAGE. 


11 


MAUL  OAK  (Quercus  chrysolepis). 

The  Maul  Oak  (Q.  chrysolepis),  when  found  growing  on  well-watered 
and  protected  slopes,  is  a  tree  40  to  60  feet  in  height,  with  large  sweeping 
branches.  On  exposed  slopes,  however,  and  on  the  upper  ridges  and 
peaks,  it  becomes  a  gregarious  shrub  with  Q.  garryana.  The  leaves  are 
oblong,  acute  or  cuspidate,  entire  on  old  trees  but  spinose-dentate  on 
young  ones  and  on  shoots.     They  are  pale  and  glaucous  above,  with 


PLATE  VII.    Quercus  californica.    (Black  Oak.) 

golden  tomentum  below.  The  acorn  is  usually  solitary,  ovate  or  oval, 
-J  to  2  inches  long,  and  borne  in  a  shallow  cup.  The  crop  of  mast  is 
uncertain  and  is  often  ruined  by  the  larvae  of  moths. 

The  range  of  this  oak  extends  from  southern  Oregon  through  the 
Coast  Ranges  and  Sierra  Nevada,  and  on  through  the  San  Bernardino 
Mountains  to  Lower  California.    It  often  reaches  an  elevation  of  9,000  feet. 

Maul  Oak  is  used  as  a  "browse"  by  sheep  and  goats,  and  sparingly 
by  cattle. 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT     STATION. 


BLACK  OAK  (Quercus  calif ornica). 

The  Black  Oak  is  a  tree  18  to  30  feet  high,  usually  with  several  large  erect 
branches.  It  is  generally  found  near  coniferous  trees,  and  apparently 
occupying  the  same  belt.  Young  trees  often  occur  in  dense  growth,  and, 
when  in  this  condition  or  when  overshadowed  by  other  trees,  grow  slowly, 
thus  enabling  stock  to  browse  on  them.  The  leaves  of  young  trees  are 
covered  with  a  dense  gray  tomentum  below,  and  are  pubescent  above. 
On  older  trees  the  leaves  are  glabrous  with  little  tomentum.     They  vary 


PLATE  VIII.    Quercus  gabryana.    (Mountain  White  Oak.) 


from  oblong  to  broadly  ovate  in  outline,  and  each  is  parted  into  about 
seven  broad  lobes.  The  nut  is  broadly  ovate,  one  inch  in  length,  and 
ripens  in  the  second  season.     The  crop  is  scanty  and  unreliable. 

The  range  of  the  Black  Oak  extends  from  the  Mackenzie  River  in 
Oregon  through  the  Coast  Ranges  and  Sierra,  and  through  the  San 
Bernardino  Mountains  to  Lower  California.  This  oak  often  reaches 
elevations  of  7,000  to  8,000  feet.     It  is  scarce  near  the  coast. 

The  flexible  texture  of  the  leaves  of  this  oak  allows  it  to  be  easily 
eaten  by  cattle  and  horses  as  well  as  by  sheep  and  goats. 


VALUE  OF  OAK  LEAVES  FOR  FORAGE. 


13 


WHITE  MOUNTAIN   OAK  (Quercus  garryana). 

Two  forms  of  this  species,  differing  only  in  range  and  height  of  indi- 
viduals, may  be  distinguished.     The  typical  form  is  a  tree  from  30  to  70 


69       g 

"Si  CO 


feet  in   height,  with  erect   rigid  branches.     Its  leaves   are  oblong  to 
obovate,  4  to  6  inches  long,  with  coarse  lobes.     The  acorns  are  sessile  or 


14  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 

shortly  peduncled,  oval  to  slightly  obovate,  about  1  to  1£  inches  in 
length,  contained  in  a  shallow  cup. 

It  ranges  from  Vancouver  Island  south  westward  through  western  Wash- 
ington, Oregon,  and  the  Coast  Ranges  of  California,  to  Santa  Cruz.  It 
is  the  only  oak  used  for  lumber  on  the  Pacific  Coast,  and  furnishes  the 
oak  lumber  for  the  furniture  factories  of  West  Berkeley. 

The  other  form  of  this  species  is  a  mere  shrub  from  2  to  6  feet  high, 
but  identical  with  the  larger  form  in  every  other  particular. 

Its  range  begins  in  an  exposed  portion  of  western  Washington,  where 
apparently  it  is  stunted  by  the  severe  sea-breezes.  Passing  along  the 
western  slopes  of  the  Cascades  in  Washington  and  Oregon,  its  elevation 
continually  increases  until  in  California  it  is  found  only  on  the  highest 
ridges  and  peaks.  Its  southernmost  range  is  Snow  Mountain  in  Lake 
County. 

The  entire  range  of  this  oak  is  swept  by  cold  driving  north  winds, 
which  apparently  serve  to  keep  the  temperature  and  other  conditions 
uniform  throughout. 

It  is  to  this  form  of  Q.  garryana  that  stockmen  turn  when  seeking 
"browse"  in  their  mountain  pasture.  It  is  gregarious  over  hundreds  of 
acres  on  the  ridges,  peaks,  and  higher  slopes  in  the  most  exposed  places 
of  the  northern  Coast  Ranges.  It  forms  thickets  to  the  exclusion 
of  everything  else  except  the  Maul  Oak  (Quercus  chrysolepis) ,  and 
occasionally  Wild  Cherry  (Cerasus  demissa). 

This  species,  almost  unaided,  supplies  pasture  for  thousands  of  sheep 
and  goats  as  well  as  cattle  and  horses,  and  not  only  keeps  them  up,  but 
actually  fattens  them.  The  stock  keep  whole  ranges  of  it  eaten  down 
often  to  within  less  than  two  feet  of  the  ground.  Aside  from  the  value 
of  the  leaves,  the  acorn,  which  is  quite  sweet,  forms  a  rich  diet  for  stock. 
The  mast  is  usually  sure  and  abundant. 

POISON  OAK  (Rhus  diversiloba). 

The  Poison  Oak  (Rhus  diversiloba)  is  usually  a  small  shrub  from  2  to 
5  feet  high,  but  occasionally  it  ascends  the  trunks  of  trees  as  a  vine,  to  a 
height  of  15  or  20  feet.  The  leaflets  are  orbicular  to  ovate,  glaucous, 
with  distinct  venation.  They  contain  an  irritating  and  poisonous  vola- 
tile oil,  which  poisons  many  persons  by  simple  contact  or  even  by  diffu- 
sion in  the  air.  The  fruit  is  pale,  about  three  lines  thick,  and  quite 
abundant. 

Rhus  diversiloba  is  everywhere  common  through  the  hilly  portions  of 
California. 

On  the  ranges  the  leaves  and  berries  are  readily  eaten  by  sheep,  goats, 
and  horses,  but  not  by  cattle,  as  far  as  could  be  ascertained  by  observa- 
tion and  numerous  inquiries.  Many  of  the  bushes  are  stripped  entirely 
of  leaves  long  before  they  would  naturally  drop  them. 


VALUE  OF  OAK  LEAVES  FOR  FORAGE. 


15 


VALUE  OF  CALIFORNIA  OAKS  FOR   BROWSING   PURPOSES. 

In  summing  up  the  value  of  these  California  oaks,  the  common  classi- 
fication into  "live,"  or  evergreen,  and  deciduous  will  be  made.  The 
former  class  includes  Scrub  Oak  and  Curl-leaf  Scrub  Oak  (Quercus 
dumosa  and  variety  bullata),  Canon  Live  Oak  (Q.  wislizeni),  and  Maul 


PLATE  X.    Rhus  diversiloba.    (Poison  Oak.) 

Oak  (Q.  chrysolepis).  The  deciduous  oaks  consist  of  Blue,  or  Rock  Oak 
(Q.  douglasii),  Black  Oak  (Q.  calij ornica) ,  and  Mountain  White  Oak 
(Q.  garryana).     The  Poison  Oak  (Rhus  diversiloba)  is  also  deciduous. 

The  live  oaks,  as  seen  in  the  previous  descriptions,  occupy  the  brush 
areas  on  the  slopes  and  ridges,  and,  except  for  a  few  isolated  specimens 


16  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 

of  Quercus  chrysolepis,  never  grow  within  the  timbered,  or  coniferous, 
belt.  These  live  oaks,  therefore,  occupy  a  continuous  belt  of  country 
which  is  free  from  snow  except  for  occasional  short  periods.  This  belt, 
for  this  reason,  is  used  as  a  winter  range  for  holding-over  stock  when 
feed  is  scarce  in  the  valleys  and  deep  snows  cover  the  mountains. 
Sheep  and  goats  are  kept  in  good  condition  on  these  live  oaks,  but 
cattle  and  horses  do  not  eat  them  to  any  extent  until  other  food  can 
not  be  obtained.  Then  this  " browse"  keeps  them  in  feed  until  other 
kinds  are  available. 

The  deciduous  oaks,  not  taking  into  account  the  Quercus  douglasii, 
which  is  of  little  forage  value,  are  found  in  the  timber  belt  or  above  it. 
The  leaves  of  the  deciduous  oaks,  in  contrast  to  the  harsh  spinescent 
ones  of  the  live  oaks,  are  larger,  lobed,  and  soft.  This  enables  cattle  and 
horses  to  eat  them  with  ease,  as  is  also  true  of  sheep  and  goats.  They 
actually  fatten  on  the  leaves  of  the  Black  Oak  and  White  Mountain 
Oak  of  these  upper  ridges  and  peaks. 

Nutritive  Value  of  the  Leaves. — From  the  observations  just  recorded 
concerning  these  several  species  of  oaks,  it  would  seem  that  the  nutritive 
value  increases  with  the  altitude.  To  verify  this,  and  to  ascertain  if 
possible  their  relative  food  values,  a  chemical  analysis  of  each  species 
was  made. 

For  the  purpose  of  this  analysis  the  leaves  were  gathered  during  the 
month  of  September,  when  they  were  fully  mature.  Only  those  which 
were  green  and  vigorous  were  taken.  These  were  dried  in  a  room  of 
ordinary  temperature,  and  were  then  ground  to  a  fine  powder. 

It  would  seem  that  the  irritating  and  poisonous  oil  of  Poison  Oak 
(Rhus  diversiloba)  is  volatile  at  a  comparatively  low  temperature.  In 
gathering  the  specimen  the  writer  was  badly  poisoned,  even  though 
gloves  were  worn;  yet  after  drying  at  ordinary  room  temperature,  and 
the  leaves  pressed  into  the  mill  with  bare  hands,  no  poisoning  effects 
followed. 

In  the  analyses  of  these  oak  leaves,  the  methods  for  foods,  as  set  forth 
in  Bulletin  No.  46,  Bureau  of  Chemistry,  U.  S.  Department  of  Agri- 
culture, were  followed.  In  this  work,  however,  some  errors  appeared  in 
the  ether  extract  and  in  the  nitrogen-free  extract.  These  errors  were 
due  to  certain  peculiarities  of  composition  of  the  oaks. 

In  the  determination  of  fat,  or  ether  extract,  quantities  of  chlorophyll, 
the  green  coloring  matter  in  the  leaves,  remained  in  the  extract.  No 
quantitative  method  being  known  for  the  extraction  of  chlorophyll,  this, 
together  with  the  gums  and  resins  which  are  contained  within  the  leaves 
or  on  the  tomentum  and  pubescence  of  the  outside,  increased  the  ether 
extract  beyond  its  true  percentage.  After  determining  the  nitrogen-free 
extract,  which  consists  of  sugar,  starch,  pentosans,  etc.,  the  percentage 


VALUE    OF    OAlCLEAVES    FOR    FORAGE. 


17 


appearedjinexplicably  high.  The  only  possible  explanation  seemed  to 
be  that  the  tannin  content,  which,  by  the  method  of  difference,  falls 
in  this  group,  had  not  been  accounted  for.  It  was  necessary,  then,  to 
make  determinations  of  tannin. 

In  determining  the  tannin,  the  method  of  Giinther  was  followed  ;  that 
is,  two  grams  of  the  substance  to  be  analyzed  was  taken  and  the  tannin 
extracted  with  hot  water,  in  which  it  is  easily  soluble,  until  a  dilution 
of  1  to  400  parts  was  obtained.  This  dilution  is  necessary  in  order  that 
potassium  permanganate  may  completely  oxidize  tannin  in  the  presence 
of  indigo-carmine.  The  oxidizing  power  of  the  indigo-carmine  was 
determined  by  extracting  all  the  tannin  by  means  of  animal  charcoal 
and  titrating  with  potassium  permanganate.  The  difference  between  the 
two  titrations  was  the  tannin  oxidized  by  the  potassium  permanganate. 

With  these  exceptions  in  the  ether  extract  and  the  nitrogen-free 
extract,  the  regular  official  method  was  followed;  and  the  table  below 
gives  the  results  of  the  analyses  of  the  different  species  of  oak  in  an  air- 
dry  condition.  As  a  means  of  exact  comparison,  these  results  were  cal- 
culated first  to  a  water-free  basis,  and  finally,  to  an  alfalfa  hay  basis. 
The  analyses  were  all  carried  out  in  duplicate  and  the  averages  found 

as  follows: 

Analyses  of  Oak  Leaves. 

Samples  Air  Dry. 


Species. 

Water. 

Ash.      Protein. 

Fiber. 

Tannin. 

Nitr'gen 

Free 
Extract. 

Ether 
Extract. 

Blue  Oak _ 

Per  cent. 
5.21 
3.90 
3.54 
6.53 
5.10 
4.59 
5.39 

Per  cent 
9.32 
9.42 
9.66 
9.62 
9.35 
9.44 
8.66 

Per  cent. 
8.32 
9.16 

10.95 
8.32 
8.15 

15.05 
6.85 

Per  cent. 
33.35 
26.79 
29.48 
30.35 
19.22 
16.26 
25.13 

Per  cent. 

5.00 
14.06 

9.62 
10.16 
10.62 

9.01 

6.42 

Per  cent. 
34.55 
31.41 
30.89 
31.52 
40.50 
40.18 
41.05 

Per  cent. 
4.25 

Scrub  Oak 

5.26 

Cafion  Live  Oak 

5.86 

Maul  Oak 

3.50 

Black  Oak 

7.06 

Mountain  White  Oak 

5.47 

Poison  Oak 

6.50 

Water-Free. 

Blue  Oak .... 

9.83 
9.80 
10.02 
10.29 
9.85 
9.90 
9.15 

8.78 
9.53 

11.35 
8.90 
8.59 

15.77 
7.24 

35.18 
27.88 
30.56 
32.47 
20.25 
17.04 
26.56 

5.28 
14.63 

9.97 
10.89 
11.19 

9.44 

6.79 

36.45 
32.69 
32.02 
33.73 
42.68 
42.11 
43.39 

4.48 

Scrub  Oak 

5.47 

Cafion  Live  Oak 

6.07 

Maul  Oak 

3.74 

Black  Oak 

7.44 

Mountain  White  Oak 

5.73 

Poison  Oak 

6.87 

Water  on  Alfalfa  Basis. 


Blue  Oak 

Scrub  Oak 

Cafion  Live  Oak 

Maul  Oak 

Black  Oak 

Mountain  White  Oak 

Poison  Oak 

Alfalfa 


10.95 

8.75 

7.83 

31.32 

4.70 

32.46 

10.95 

8.72 

8.48 

24.83 

13.03 

29.11  | 

10.95 

8.92 

10.11 

27.21 

8.88 

28.52  ' 

10.95 

9.16 

7.92 

28.91 

9.70 

30.03 

10.95 

8.77 

7.65 

18.03 

9.96 

38.01 

10.95 

8.82 

14.04 

15.18 

8.41 

37.50  ! 

10.95 

8.15 

6.44 

23.65 

6.04 

38.64  i 

10.95 

6.43 

17.60 

22.63 

39.31 

3.99 
4.87 
5.41 
3.33 
6.63 
5.10 
6.13 
3.0S 


18  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 

In  the  discussion  of  the  chemical  analysis  of  these  species,  alfalfa  hay- 
is  selected  for  comparison  because  alfalfa  seems  to  be  the  best  and 
commonest  forage  plant  in  California.  A  comparison  with  this  plant, 
then,  naturally  sets  forth  the  value  of  oak  leaves  for  forage  to  better 
advantage  than  a  comparison  with  any  other  stock  food. 

Ash  Content. — In  comparing  the  ash  content  of  oak  leaves  and  alfalfa, 
it  is  noted  that  the  ash  of  oaks  varies  but  little  in  various  species.  This 
variation  is  not  more  than  four-tenths  of  one  per  cent,  while  the  average 
ash  for  all  the  species  is  somewhat  greater  than  8.75  per  cent.  This 
percentage  is  2£  per  cent  greater  than  in  alfalfa  hay. 

As  all  the  mineral,  and  hence  the  bone-forming,  materials  of  the 
plant  are  in  the  ash,  oak  leaves  have  thus  a  greater  value  for  growing 
stock  than  has  alfalfa. 

Protein  Content. — Proceeding  to  the  protein,  or  muscle-forming  content, 
greater  variations  are  encountered.  The  comparison  shows  alfalfa  to 
contain  more  than  twice  as  much  protein  as  any  of  the  oaks,  with  the 
exception  of  two  species,  Quercus  wislizeni  and  Q.  garryana.  The  former 
averages  10.11  and  the  latter  14.04  per  cent.  Quercus  garryana,  there- 
fore, approaches  alfalfa  closely.  The  other  species,  though  falling  far 
below  alfalfa,  are  not  poor  in  protein.  The  average  is  nearly  8  per  cent, 
which  is  one-half  of  one  per  cent  higher  than  oat  hay — the  best  of 
cereal  hays. 

These  analyses  indicate  that  oak  leaves  are  superior  in  muscle- forming 
ingredients  to  non-leguminous  hay;  that  one  species  (Quercus  wislizeni) 
is  equal  to  bur-clover  hay;  and  the  best  species  (Quercus  garryana) 
almost  equal  to  alfalfa  hay. 

Crude  Fiber. — In  oak  leaves  the  crude  fiber  is  as  variable  as  the  pro- 
tein, ranging  from  over  30  per  cent  in  Quercus  douglasii  to  15  per  cent 
in  Q.  garryana.  With  the  exception  of  two  of  the  deciduous  oaks, 
Quercus  calif ornica  and  Q.  garryana,  the  oak  leaves  are  considerably 
higher  in  crude  fiber  than  alfalfa.  This  crude  fiber,  or  roughage,  in  oaks 
tends  to  produce  a  wide  nutritive  ration. 

Ether  Extract. — The  fat,  or  more  correctly  speaking,  the  ether  extract, 
w  considerably  higher  than  in  alfalfa  in  all  the  species,  and  increases  to 
twice  as  much  in  Quercus  wislizeni  and  Q.  californica.  This  ether 
extract  does  not  represent  pure  fat,  but  includes  the  chlorophyll,  waxes, 
and  resins,  which  can  not  be  separated  from  the  true  fat.  These  waxes 
and  resins  serve  to  protect  the  leaves  from  drying  winds  and  inclement 
weather,  and  usually  occur  in  the  tomentum  or  pubescence  which  cover 
some  leaves.  In  some  cases,  as  in  Quercus  californica,  the  waxes  and 
resins  are  distasteful  to  stock,  thus  decreasing  their  forage  value. 


VALUE  OF  OAK  LEAVES  FOR  FORAGE.  19 

Nitrogen-Free  Extract. — In  oaks  the  nitrogen-free  extract,  consisting 
of  starch,  sugars,  pentosans,  etc.,  does  not  equal  alfalfa  in  any  species, 
and  in  Scrub  Oak  falls  as  far  below  as  10  per  cent.  This  fact  indicates 
a  lower  fattening  and  heat-producing  power  than  in  alfalfa. 

Tannin. — Tannin  is  an  astringent  principle  found  in  many  plants. 
Aside  from  its  astringent  properties,  it  is  acrid,  and  therefore  offensive 
to  the  palates  of  animals.  In  the  stomach,  it  precipitates  the  pepsin 
and  peptones,  thus  preventing  the  formation  of  dextrose  and  hindering 
digestion.  Great  thirst  and  constriction  in  the  digestive  tract  usually 
follow  an  overdose  of  it.  These  effects  are  not  so  marked  in  some  tan- 
nins as  in  others,  for  some  do  not  have  so  great  a  precipitating  power  as 
do  others. 

In  determining  the  tannins  in  the  oaks,  it  was  found  to  vary  greatly 
in  the  different  species,  but  did  not  serve  as  an  infallible  indication  of 
the  value  of  the  leaves  for  forage.  For  example,  Quercus  douglasii,  which 
is  the  poorest  forage  oak  analyzed,  is  lowest  in  tannin,  while  Q.  dumosa, 
a  species  preferred  by  sheep  and  goats,  contains  13  per  cent,  the  largest 
amount  of  tannin  determined  in  any  one  species. 

The  average  of  tannin  for  all  the  oaks  is  a  little  over  10  per  cent.  In 
tasting  the  powdered  specimens  of  the  various  species,  the  intensity  of 
acridity  perceived  coincides  with  the  tannin  percentages.  In  comparison 
with  oak  leaves,  alfalfa  contains  an  inappreciable  amount  of  tannin. 

Water. — Although  the  water-content  of  the  oak  leaves  was  placed  on 
an  alfalfa  hay  basis,  this  does  not  indicate  their  true  comparison  when 
both  are  green.  Green  alfalfa  contains  80  per  cent  of  water,  which  is 
from  10  to  20  per  cent  higher  than  that  in  the  various  species  of  oaks. 
This  shows  the  oak  leaves  to  be  a  somewhat  more  concentrated  feed  in 
regard  to  protein,  ash,  and  nitrogen-free  extract,  than  appears  in  the 
comparison  on  an  alfalfa  hay  basis. 

Injurious  Constituents. — Judging  from  the  results  of  the  chemical 
analyses  of  these  oak  leaves,  they  would  seem  to  occupy  a  high  place 
among  forage  plants.  This  would  be  the  case  were  it  not  for  excessive 
amount  of  three  of  the  chemical  constituents;  namely,  crude  fiber,  resins 
and  waxes,  and  tannin. 

The  high  percentage  of  crude  fiber  taken  together  with  the  low  per- 
centage of  nitrogen-free  extract  produces  a  coarser  and  less  nutritious 
feed  than  leguminous  crops. 

The  resins  have  pungent  and  disagreeable  flavors,  which  render  them 
distasteful  to  stock.  A  good  example  of  this  is  seen  in  the  Quercus 
californica,  before  cited.  The  leaves  of  the  young  trees  and  shrubs  of 
this  species  contain  no  more  tannin  than  those  of  most  of  the  other 
species,  are  only  1-J  per  cent  below  alfalfa  in  nitrogen-free  extract,  have 
a  fair  amount  of  protein,  are  low  in  crude  fiber,  and  are  large  and  soft. 


20  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION. 

These  qualities  should  produce  a  feed  superior  to  oat  hay.  This  is  not 
the  case,  however,  for  stock  avoid  it  to  a  great  extent  on  account  of  the 
resins  and  waxes  in  the  dense  tomentum  covering  the  leaves.  These 
waxes  and  resins  serve  as  a  protection  against  drying  winds  and  severe 
weather,  and  all  the  oaks  have  more  or  less  of  them. 

As  compared  with  the  crude  fiber  and  resins,  tannin  of  oak  leaves,  as 
before  stated,  is  not  only  bitter  and  astringent,  but  interferes  with 
digestion. 

Conclusion. — In  summing  up  the  value  of  the  forage  oaks,  from  chemi- 
cal analyses  and  observations  in  the  field,  the  conclusion  is  reached  that 
the  facts  observed  in  the  field  coincide  in  most  cases  with  those  deter- 
mined by  analysis.  For  instance,  the  deciduous  oaks  possess  a  higher 
nutritive  value  than  the  live  oaks  and  are,  as  would  be  expected,  more 
readily  eaten  by  horses,  cattle,  sheep,  and  goats.  In  some  cases,  how- 
ever, certain  physical  conditions  modify  these  relations.  This  is  true 
in  the  case  of  the  live  oaks.  These  contain  a  sufficiently  high  proportion 
of  nutrients,  and  yet  only  sheep  and  goats  thrive  upon  them.  This  is 
due  to  the  thick,  harsh  leaves  with  their  spinescent  teeth,  which  prevent 
horses  and  cattle  from  relishing  them. 

Pasturing  Oaks. — Although  all  stock  prefer  the  deciduous  oaks  of  the 
higher  altitudes,  yet  indiscriminate  pasturing  causes  much  damage  to 
the  forests  and  ground-cover.  When  sheep  and  goats  are  allowed  to 
browse  on  the  deciduous  oaks  of  the  timbered  area,  they  kill  the  seedling 
conifers  by  nibbling  and  trampling,  kill  the  shrubs  by  over-browsing, 
and  cut  up  the  slopes  in  trails  which  become  deep  gullies  during  the 
rainy  season.  This  could  be  avoided  by  pasturing  the  sheep  and  goats 
on  the  ''live  oaks"  of  the  lower  chaparral  or  brush  areas,  the  only  neces- 
sary precaution  being  to  prevent  too  many  congregating  in  one  place, 
thus  avoiding  too  much  trampling  and  gullying. 

Since  cattle  and  horses  are  unable  to  thrive  on  the  live  oaks,  and 
since  they  do  not  browse  close  enough  to  kill  shrubs,  never  browse  on 
young  conifers,  nor  cut  up  slopes  by  trails,  they  may  profitably  be  pas- 
tured on  the  timbered  areas  and  on  the  higher  altitudes. 

Thus,  this  oak  area,  comprising  half  the  whole  State,  can,  by  a  con- 
servative and  well-regulated  system  of  browsing,  be  made  to  pasture 
sheep  and  goats  throughout  the  year,  and  all  stock  during  the  summer 
months;  and  also  during  seasons  of  drought  or  when  winter  conditions 
make  other  feed  inaccessible. 


VALUE  OF  OAK  LEAVES  FOR  FORAGE.  21 


BIBLIOGRAPHY. 


1.  Flora  of  Western  Middle  California.     Jepson. 

2.  Silva  of  North  America,     Sargent. 

3.  Check  List  of  the  Forest  Trees  of  the  United  States,  their  Names 

and  Ranges.     Bulletin  No.  17,  Bureau  of  Forestry.    Sudworth. 

4.  Stock  Ranges  of  Northwestern  California.     Bulletin  No.  12,  Bureau 

of  Plant  Industry.     Davy. 

5.  Feeding  of  Farm  Animals.     Bulletin  No.  132,  College  of  Agricul- 

ture, University  of  California.     Jaffa  and  Anderson. 

6.  Feeds  and  Feeding.     Henry. 

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ciation of  Chemistry.     Bulletin   No.  46,  Bureau  of  Chemistry, 
U.  S.  Department  of  Agriculture. 

8.  Plant  Analysis.     Dragendorff. 

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